Study of the transfer function of atmosphere to operation range of IRFPA

There are much more need to characterize and evaluate performance of IRFPA in field. MRTD, MTF, NETD and operating range R are some of the key parameters of IR devices and used to characterize their performance. Around of these parameters there are two ways: analysis in theory and test. The research of these parameters in theory can be used to predict the performance of IR devices and these parameters can be proved by experiments. Whereas these parameters are hard to be tested in field, their test reports are based on experiment in laboratory. So it is very hard to explain or predict the test results of IR devices in theory because of the influence of atmosphere. This paper presents research of transfer function of atmosphere. A model of transfer function with the modified absorption and scatter coefficient is introduced based on the theory of transfer function. The operating range can be modified by transfer function of atmosphere. The experiment results show this model can be used together with operating range in some circumstances. It could be used in the predicting the operating range of IR devices in theory.